ref(api): Update DELETE users/ to support hard deleting

[evanpurkhiser]

This is a replacement for the web.frontend.admin endpoint that is used
in the admin manage interface (primarily for open source sentry) to hard
delete accounts.

I'll add a few more tests to be 100% sure things are right here. But am
looking for some API review from people who write APIs more than me

Specifically trying to remove this

sentry/src/sentry/web/frontend/admin.py

Lines 73 to 89 in b062edd

	def remove_user(request, user_id):
	if six.text_type(user_id) == six.text_type(request.user.id):
	return HttpResponseRedirect(absolute_uri('/manage/users/'))
	try:
	user = User.objects.get(pk=user_id)
	except User.DoesNotExist:
	return HttpResponseRedirect(absolute_uri('/manage/users/'))
	form = RemoveUserForm(request.POST or None)
	if form.is_valid():
	if form.cleaned_data['removal_type'] == '2':
	user.delete()
	else:
	User.objects.filter(pk=user.pk).update(is_active=False)
	return HttpResponseRedirect(absolute_uri('/manage/users/'))

[evanpurkhiser]

This used to just assume you were deleting yourself, this updates things so you can delete someone else (with the proper authorization of course, which happens in UserEndpoint)